This invention relates to improvements in machining tools and in particular to improvements of broaching machines. Broaching machines use a tool which gradually cuts away pieces of a material in a very fast and efficient process. The broaching machine requires less time than a comparable boring, milling, and finishing of an aperture and also attains a relatively equal precision. The broaching process requires the article or workpiece to be secured to a support table in a stable manner so a broaching tool, attached to the ram, can proceed in a perpendicular direction with respect to the supporting table and cut a slot in the workpiece.
The tool used is a long member with a number of cutting teeth of about the same width, arranged in a tapered fashion, shallow teeth to deep cutting teeth. The shallowest of the cutting teeth engages with the article first initiating the cutting and then succeedingly deeper cutting teeth pass through the article with each tooth removing a little more of the workpiece. The ram holding the broaching tool makes a cutting stroke in a downward fashion through the workpiece, driven with great force by a hydraulic ram which applies a steady and smooth cutting stroke.
Typically in broaching a deep slot or form with a broach machine of this type, a means for advancing the work (i.e. the article to be broached) in increments toward the ram allows the article to be worked upon in progressive stages. After the article is advanced forward, it is held in position and the broaching tool makes a downward cutting stroke. If more material is to be cut away, the article is withdrawn away from the ram, the broaching tool ascends with the slide, the article again is moved forward by one increment, and the broaching tool descends for a second cut, and so on. A sensing means determines when the article is finished, at which time it is withdrawn and tilted up ready for unloading and loading of a new article, and the broaching tool returns to its original top position.
Previously the combination of the tooling for securing the article or workpiece and the support structure for producing the shuttling action, and the tilting motion resulted in the workpiece being mounted high above the table. This prior configuration allowed horizontal force components produced by the cutting action coupled with a substantial height above the hinge point to create a moment around the hinge point producing a tilt back reaction in the table. The present invention uses a movable shuttle support incorporated in the table, allowing the tooling to secure a workpiece closer to the table surface. By mounting the work piece or article closer to the table, less moment is exerted around the hinge point.